This application claims the benefit of Japanese Patent Application No. 2000-180921, filed on Jun. 16, 2000, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a receiver for digital broadcasting, and more particularly, to a receiver capable of simultaneously receiving a plurality of digital broadcast waves.
2. Description of the Related Art
Generally, when data is transmitted in a digital broadcasting system, the sending side encodes data for transmission with an error-correcting code, such as a Reed-Solomon code or a Trellis code, before the data is transmitted. By encoding data intended for digital broadcast transmission with an error correcting code, a receiver can perform error correction on the received data in events when errors occur during the transmission process. One type of error that often occurs is a random error. A random error is a loss of data within the data transmission stream of relatively short period. Random errors are usually caused by radio interference, such as atmospheric noise and/or when a signal fades.
However, relatively long periods of data loss called burst error also occur often within a transmitted data stream. When burst errors occur, it is often difficult for a receiver to perform error correction because the number of data bits lost may exceed the redundancy of an error-correcting code.
Data interleaving is one measure that has been proposed for digital broadcasting to reduce the occurrence of data loss due to burst error. FIG. 1 schematically illustrates a data interleaving process that may be performed by the transmitting and receiving ends in a digital broadcast system. As shown in FIG. 1, an original data sequence 1 intended for reproduction includes a data sequence b0-b9 of a program. Before transmitting the data sequence 1 of the original program, the sending side changes the order of a data sequence according to a prescribed procedure (interleaving) to produce an interleaved data sequence 2. After receiving the data sequence 2, the reception side changes the order of the data sequence according to an opposite procedure (de-interleaving) so that the data is rearranged back into the order of the original data sequence 1.
Data sequence 3 illustrates a case when a burst error occurs during the transmission data sequence 2, resulting in a loss of a relatively long continuous period of data 3a-3c (respectively representing the loss of interleaved data b1, b4 and b7). However, a de-interleaving procedure performed on the reception side of the system distributes this continuous data loss portion 3a-3c over an entire data sequence, as shown by data sequence 4. In other words, the reception side can process a burst error consisting of a long period of data loss into several relatively short periods of data loss, i.e., the reception side""s de-interleaving converts the burst error 3a-3c into random errors 3A, 3B and 3C, as shown in data sequence 4. Thereafter, since the burst error 3a-3c is distributed as a plurality of short duration random errors, error-correction may be properly performed on the data sequence 4 by using error-correcting codes to restore the lost data to its original state (e.g., data sequence 1) shown by data sequence 5 for program reproduction.
The extent to which transmission data is interleaved correlates with ability for correction of errors that occur during transmission. By increasing the degree that the order of a transmission data sequence is changed, longer periods of burst error in the transmission data sequence may be processed for correction by an error-correcting procedure on the receiving end.
However, the reception side can perform de-interleaving only after receiving all of an interleaved data sequence. Consequently, when the amount of interleaving performed on transmission data is made larger, a corresponding delay increases between of a start of an actual program output as video and/or audio and the reception of the digital broadcast transmission data.
Thus, there remains a need in the art for a receiver for digital broadcasting that enables adequate error correction in a plurality of transmitted program data of a digital broadcast waves while allowing for minimal delay between reception of the waves and reproduction of the transmitted program.
Accordingly, the present invention is directed to a receiver for digital broadcasting that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
One aspect of the present invention is a receiver for digital broadcasting that can produce a reproduction output of a broadcast content early after a start of reception.
Another aspect of the present invention is a receiver for digital broadcasting that includes a plurality of receiving systems for respectively receiving a plurality of broadcast signals, and the receiver includes a memory that stores information relating to selection of at least one receiving system of the plurality of receiving systems in accordance with a reception state of the at least one receiving system.
Still another aspect of the present invention is a receiver for digital broadcasting that is capable of simultaneously receiving a plurality digital broadcasts waves carrying digital data that are different in the amount of interleaving performed on the digital data within each wave prior to transmission.
In yet another aspect of the present invention, a receiver of digital broadcasting initially selects a digital broadcast wave among a plurality of received digital broadcast waves when a receiving operation is initiated, and the selected broadcast wave includes data that are not interleaved or have a relatively small amount of data interleaving among the plurality of digital broadcast waves.
In the present invention, when a plurality digital broadcast waves are of the same program, a user can experience a broadcast of a desired channel in a short time after the start of reception of the digital broadcast waves by the receiver. Therefore, the invention makes it possible to provide broadcast information quickly to a user, regardless of whether or not interleaving is performed on transmitted data received by each receiving system of the receiver and regardless whether the amounts of interleaving are different between the plurality of receiving systems of the receiver.
Additional aspects and advantages of the invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The aspects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the invention, as claimed.